Electrical transmission of power



(No Model.)

W. D. BALDWIN. ELECTRICAL TRANSMISSION OF POWER.

N0. 54?;834. Patented 001:. 15, 1895.

AN DREW lGMnA M. PnoTou nQwAsmNGmmnQ UNrrnn STATES PATENT OFFICE.

\VILLIAM D. BALDW'IN, OF YONKERS, NEW YORK.

ELECTRICAL TRANSMISSION OF POWER.

SPECIFICATION forming part of Letters Patent No. 547,834, dated October 15, 1895.

Application filed July 3,1894. Serial No. 516,426. (No model.)

aZZ whom it may cancer-n: Be it known thatl, WILLIAM D. BALDWIN,

a citizen of the United States, residing at- Yonkers, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Electrical Transmission of Power, of which the following is a specification.

My invention relates to electrical transmission of power, and more especially to the use of electric motors for performing mechanical operations where it is necessary or desirable to run the motors at different speeds and at different torques, and the object of my invention is to provide means whereby this can be accomplished in an economic and practical manner; and to these ends my invention consists in the various features of construction and arrangement of parts having the mode of operation substantially as hereinafter more particularly pointed out.

In order that the principles ofmy invention can be more readily understood, in the accompanyingdrawingl have illustrated a diagrammatic arrangement of devices and circuits embodying my invention. v

lVhile my invention, broadly, is adapted for use in many and various purposes in the transmission of power, it is especially adapted for use in connection with electric elevators, and in the present instancel have shown and described its application to such elevators, although, of course, my invention is not intended to be limited to such use.

My invention relates to the general system of electrical transmission of power set forth in United States PateIitNo.463,8l)2, granted to H. W. Leonard November 24, 1891, and I therefore do not deem it necessary to set forth in detail the general principle of operation of the invention; but it is sufficient to say that the generator is kept constantly running and the working motor has its field constantly excited, and these, with other features of construction and arrangement, occasion more or less Waste of power and unnecessary wear and tear on the machinery.

It is one of the objects of my present invention to provide means to start the whole system of generator and motors when wanted and to stop it when not in use, and to so arrange and construct the elements of the system that the working motor not only can be readily controlled so as to do the work required, but that the current shall be utilized to the best advantage and used only when necessary and that the parts shall not be subject to wear and tear more than is required in performingthe functions desired.

With these general statements of the purposes and objects of my invention, I will now proceed to describe the particular embodiment thereof illustrated in the accompanying drawing.

For the purpose of clearness, I have shown what might be termed a plan view of the motors and generators and elevator windingdrum, and I have shown the elevator-car and suspension-ropes in sectional and side View, while the electrical switches and circuits are arranged so as to clearly display their mode of operation and connections in a manner to be readily understood by those skilled in the art.

The elevator-car A is connected by a suspension-rope B, passing over a sheave B, with the winding drum 0 in any usual and well-known manner, and this drum is operated by the working motor W M in the present instance, the said motor being shown as provided with a worm on the armature-shaft D, engaginga worm-wheel D on the shaft of the Winding-drum C, the working motor and winding-drum being preferably mounted upon the same base, and the car can be raised and lowered inthe usual manner by reversing the direction of motion of the drum, and this is accomplished by reversing the direction or rotation of the armature-shaft of the working motor. The field-magnet coils of the Working motor are supplied with a current from a constant source, as the distributingmains of an electrical system, so that there will be a constant field in the motor, and the current for the armature of the working mofield. In the present instance I have shown a switch E, mounted on the car A and provided with suitable connections and resistance devices, whereby the current may be taken from the mains and led to the switch and pass through the switch and the resistances to the field-magnet coils of the generator, and these conductors (which may be conveniently grouped in a cable) are arranged to move with the car and be controlled by the operator thereon.

The armature of the generator is driven by some suitable device at a constant speed, and

-it will be seen that by regulating the current through the field-magnet coils of the generator a current will be generated thereby of a relative pressure to drive the working motor at any desired speed, and by removing the resistance in the circuit of the field-magnet coils of the generator by operating the switch device or otherwise the field-magnets will be more strongly energized and the speed of the working motor will be varied in accordance therewith, and with a working motor having a constant field it can be run at any speed, from the slowest to the greatest without waste of energy and be under the complete control of the operator on the car. The armature of the generator G is driven in the present instance by an electric motor M, the field-magnet coils of which are shown as excited from the main circuit, so as to produce a constant magnetic field, and the armature of said motor is also supplied with current from the same source, and included in the circuit of the armature is an automatic-controlling device F, which varies the current flowing through the armature in accordance with the counter-electromotive force in the motor. In this instance I have shown the well-known automatic device patented to Rudolph Eickemeyer, June 23, 1891, No. 454:,462, and the details of its construction and operation need not therefore be set forth, as they are well understood by those skilled in the art.

The circuits of the field-magnets of the motor M and the working motor W M are controlled by a cut-out switch H, which also controls the armature-circuit of the motor M, and this switch is arranged to be operated electromagnetically by the operator on the car, and I have shown a magnet I, the armature I of which is connected to the switch-arm I*I- of the switch H, which arm is shown as pivoted in the lugs H and controls the terminals h h of the switch, which terminals are connected to the mains supplying current to the system; and while I have shown a simple single-brake switch it is understood that any other wellknown form of switch may be used in place thereof, this being shown for simplicity of illustration.

The coils of the magnet I are connected in a circuit leading from the mains and passing through the switch E on the car A and are controlled by the operator, so that in the normal condition, with the car at rest, there is no current passing through any portion of the apparatus. When the switch on the car is operated, the circuit is closed through the magnet I, and this in turn operates the switch I-I, closing the circuit through the field-magnet coils of the motor M, and the working motor \V M and the armature of the motor M, as well as the current, through the variable field-magnet coils of the generator G, and the Whole system is, therefore, under the positive control of the operator by means of a single switch on the car. It will be understood that the automatic resistance cut-out or controller F is connected to the switch H by a connection F, which positively moves the weighted arm F in such a manner as to include all the resistances of the safety devices in the circuit when the circuit is open, and when the switch H is closed the arm F is positively moved to the position shown in the drawing, so as to allow the resistances to be cut out or in in accordance with the current passing through the solenoid F which controls the core F connected to the arm F to include more or less of the resistance devicesf, in accordance with the current flowing through the coils of the solenoid, in a manner well understood.

For convenience ofillustrationIhave shown a separate motor M and generator Gr, although any well-known form of motor-generator may be used; but in the arrangement shown the armatures of both the motor and generator are mounted on the same shaft or are connected together, and I preferably make the connection of sufficient weight, or in some instances apply a fly-wheel K to the connection, so that the armatures will continue their rotation a certain time after the current is cut off from the motor, the momentum of the armatures maintaining their rotation. This is an important feature in the operation of elevators which have to be started and stopped at frequent intervals at the different floors of a building, as it avoids to a greater or less extent the objections incident to the sudden stopping and starting of the mechanism,and avoids also a loss of power. Thus, when, for instance, the car stops at any floor and the current is cut off by the operator, so as to no longer excite the motor or generator, the armature-shaft of the motor-genera tor will maintain its rotation for a considerable time-several minutes, if necessary and when the current is again thrown on it will be thrown onto a motor already in actual motion, and this prevents sparking or burning of the brushes or switches, and also aids in preventing the abrupt action or sudden impulse which is usually imparted to the mechanism, and also allows a great saving of power, not only in starting the cage from a state of rest, but preventing the consumption of electric energy absolutely during the time that the car is at rest, and avoiding the consumption of current in the resistance-box, as ordinarily used. While I have shown the armatures of the motor-generator on the same shaft, it is evident that they could be on sepa rate shafts and be geared together to run at different speeds or otherwise, as desired.

I will now describe the circuits as shown in the accompanying drawing, so that the operation of the device will be understood. Oonnected with the source of electricity or mains plus and minus are the conductors 1 2, leading to the switch E on the car, the conductor 1 being connected to the switch-arm c and the conductor 2 being connected to the switcharm 6'. This switch is shown in a conventional manner for the sake of clearness, and the contacts are displayed and shown, a few in number, and there is a single resistance 3 included in the field-magnet circuit; but of course in actual practice there will be any desired number. The terminals of the fieldmagnet coils of the generator G are connected by conductors 3 and 4 to the contacts 3 and 4 of the switch E on the car, and these terminals are arranged so that the direction of the current through these conductors can be changed to change the direction of the cur rent supplied to the armature of the working motor. Also mounted on the switch is a contact or contacts 5, connected with a conductor 5, which leads to the magnet I, and from thence the circuit leads to the minus main, joining at the point 5. The conductor 7 leads from the plus main through the armature of the motor M, and thence the conductor passes to the automatic regulator F, including the resistances f, the contact-arm F, the coils of the solenoid F and thence by the conductor 6 through the switch 11, and by the conductor 8 to the minus main. Branching from the conductor '7 is a conductor 13, which includes the fielctmagnet coils of the motor M as well as the fieldmagnet coils of the working motor NV M, and thence the current flows through the conductor 6 through the switch H to the minus main, as before. The conductor 12 connects the armature of the motor-generator with the armature of the working motor IV M.

In the condition shown in the drawing all the circuits are open and no current is flowing through any part of the apparatus. Supposing, now, the operator on the car moves the switch E to the right, the current from the main may be traced as follows: Commencing at the plus main, through conductor 1 to the switcharm e, the contact-terminal 3, through the resistance 3 and the conductor 3, through the field-magnet coils of the generator, and out, by the conductor 4, to the contact 4 on the switch on the car. Thence the current divides, a portion flowing directly through the switch-arm e, by the conductor 2, to the minus main, and another portion passing from the contact 4 to the contact and the conductor connected therewith, energizing the magnet I, and to the minus main. It will thus be seen that the field-magnet coils of the gener-. ator G are included in the main circuit, which includes a resistance, while the magnet I 0perates the switch 11 to close the circuit by means of conductors 7, 13, 6, and 8, so that the field-magnet coils of the motor M and the working motor W M are energized with the full force of the current from the main, while the circuit through the armature of the motor M includes the automatic cut-out F, and which includes the resistancef, which is automatically cut out or varied in accordance with the counter-electromotive force of the motor M. By moving the switch E to the next contact, more or less of the resistance 3 is cut out of the field-magnet circuit and the strength of the current generated by the generator G is varied, and this, flowing through the conductor 12, drives the working motor in the proper direction and with the desired speed, which speed can be varied by varying the resistance 3. in the field-magnet circuit.

When it is desired to stop the elevator, as at an intermediate floor or at the end of its travel, the switch E is brought to its normal position, gradually cutting in the resistance 3' until the circuit is broken. When it is desired to operate the motor in the opposite direction, the switch E is moved to the left and the circuits are substantially the same, with the exception that the current flows through the field-magnet coils of the generator G in a direction opposite to that in the former instance, and is regulated the same way by the same resistance 3'.

It will be observed, also, that when the switch E is moved in either direction from its normal position, it closes the circuit through the magnet I, and when it is turned to its normal position it breaks the circuit, and the magnet I, being de-energized, the switch H is operated to instantly break the current through the motors connected therewith.

As the motor used is relativeiy small and its armature rotates at a relatively high speed, there is a certain amount of momentum in the armature-shaft which causes it to rotate more or less after the current is cut off, and especially when there is a fly-wheel or equivalent connected with the armature which tends to prolong the time of its rotation. I take advantage of this in operating elevators in making the stops at intervening floors, which are usually of short duration, and by closing the circuit through the motor before the armature-shaft ceases its rotation there is less liability to sparking or burning of the brushes or switches and a less abrupt action or strain on the motor and'generator, in view of the fact that the machine is in actual motion when the circuitis closed. Moreover, this requires the expenditure of less electric energy to start the elevator, as the inertia of the motor-generator does not have to be overcome by the current in the first instance. In other words, with this arrangement, while there is absolutely no current flowing through the motor while the car is at rest, when the car is started, before the armature-shaft ceases its ICC IIO

rotation it is caught on the fly, so to speak, and the result is that thereis a very considerable saving of power as well as strain on the operating parts. Of course the same advantage may be taken of this motion of the shaft at the top and bottom of the well of the cage if the stops are not too long. It will be understood, of course, that the working motor does not continue its rotation after the current is stopped, for the reason that the resistance of the load and the connecting mechanism is sufficient to stop the working motor the moment the force necessary to drive it is withdrawn, and of course there is no appreciable current produced in the generator when the current of these field-magnets is broken at the switch.

It is not deemed necessary to set forth in detail the advantages of the construction, arrangement, and mode of operation of my invention, as they will be apparent to those skilled in the art, and it will be seen that I am enabled to control the Whole system from a switch at a distant point from the devices, and which moves with the elevator-car or otherwise, and I am enabled to completely out out all the circuits of the apparatus when the car is not in actual motion, thereby saving a large amount of current, and by taking advantage of the momentum of the motor-shaft I am further enabled to save current, as well as to avoid shocks or strains due to closing the circuit through a stationary motor, and, moreover, the necessary counter-electronictive force of. the motor is more quickly attained, so that the automatic switch will operate more quickly and the whole movement of the elevator will be more regular and even than in the usual constructions.

WVhat I claim is- 1. The combination with a working motor having a constant field, otagenerator the armature of which is connected to the armature of the working motor, a motor having a constant field connected to the generator, means for automatically varyingthe current through the armature of the motor, and a switch at a distant point controlling the current through the field-magnet coils of the generator, substantially as described.

2. The combination with a working motor having a constant field, of a car connected to be operated by said working motor, a generator having a variable field the armature of which is connected with the armature of the working motor, a motor having a constant field for operating the generator, a cut-otit switch controlling the circuits through the fields of the motors, and aswitch upon the car controlling said cut-out switch and controlling the current through the field of the generator, sub stantially as described.

3. The combination with a working motor and car connected to be operated thereby, of a generator having a variable field and the armature of which is connected with the armature of the Working motor, a motor having a constant field connected with the generator, an armature circuit for said motor including an automatic resistance device, a cut-out switch controlling the circuits of the motors, and a switch on the car controlling the cut-out switch and varying the current through the field of the generator, substantially as described.

4. The combination with a working motor and car connected to be operated thereby, ot' a generator connected to operate the working motor, a motor connected to operate the generator, a cut-out switch controlling the circuit of the motors, a magnet controlling said outout switch, and a switch on the car controlling said magnet and controlling the current of the field of the generator, substantially as described.

5. The combination with a working motor and a car connected to be operated thereby, of a motor generator connected to operate the working motor, a cut-out switch controlling the operating circuits of the motor generator, and a switch on the car controlling said outout switch and controlling the current in the field of the generator, substantially as described.

6. The combination with a working motor and car connected to be operated thereby, of a motor generator connected to drive the working motor the armature shaft of the motor generator being mounted to rotate freely under the action of momentum after the current is out oh", and a switch on the car controlling the current through the motor and fieldmagnets of the generator, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

. WM. D. BALDWIN. Witnesses:

H. W. BUCKLEY, NORTON P. OTIS. 

